Nagravision S.a.

Brecht Wyseur

Jean-Bernard Fischer

Christian Schwarz

Karine Villegas

Laurent Dore

Eric Piret

Laurent Doré

Patrik Marcacci

Yasser Belaidi

Fabien Gremaud

Nicolas Fischer

Marco Macchetti

Christian Mönch

Klaus Kursawe

Yihui Xu

Asfandyar Orakzai

Belaïdi Yasser

The present disclosure relates to the exchange of information between a message sending device and a message receiving device with message authentication and proposes to reduce the time required for message authentication by pre-computing a message tag, such as a MAC, and subsequently replacing the computation of the MAC when the tag is to be validated (or indeed also on sending) by a table look-up. The approach requires a set of messages and works particularly well for small sets of messages, for example as small as two or three messages, or less than five or ten messages. The approach finds particular application in control networks where control decisions have to be taken quickly and securely, for example in the control of a vehicle, for example an autonomous vehicle, or the control of a smart electricity grid.

Sending and receiving messages

A system and a method for protecting code are provided. Extraction of code to be protected takes place during an object-to-object transformation and that code is replaced with fake binary code. The extracted code to be protected may then be encrypted or otherwise obscured and stored in a separate region of an object file. A prior source-to-source file transformation can be provided to isolate and mark the code to be protected, and to inject additional source code to handle later decryption.

On demand code decryption

The present disclosure relates to the use of cryptographic techniques to facilitate local decision making at a gateway device () interfacing between an operator device () and edge devices (), for example as can be found in Internet of Things infrastructures. Local decision making is facilitated in the context of end to end encryption of data between the edge device and operator device by enabling a function of the data to be computed at the gateway () without decrypting the data, for example using Functional Encryption (FE). The gateway determines an action based on the computed function, for example whether to transmit the data to the operator device (). Examples of edge devices are video surveillance cameras or utility consumption meters but the disclosure is applicable to any edge device that produces data to be transmitted with end to end encryption. The disclosure is also not limited to IoT infrastructures.

Local decision making

A block cipher method and apparatus using round repetition for providing, from a plaintext message (), a ciphertext message () and a global tag () is disclosed. The plaintext message is converted into a plurality of ordered plaintext blocks () which are successively processed during a round for computing:—a cryptogram () by encrypting input data () using a single cryptographic key, said cryptogram comprising a first segment () and a second segment ()—a ciphertext block () by performing a first operation () using, as operands: said first segment () said current plaintext block () and said second segment (). At each next round said input data is newly determined based on the current ciphertext block and an updated reproducible data. The ciphertext message is determined by concatenating the ciphertext blocks and the global tag by a second operation () using computed authentication local tags as operands.

Block cryptographic method for encrypting/decrypting messages and cryptographic devices for implementing this method

The present disclosure relates to software tampering resistance. In one aspect, a method for generating protected code is provided, comprising identifying a primary function in code to be obscured, the primary function being a function used to verify the integrity of the code run-time. The method then comprises generating a finite state machine from the primary function, wherein a state of the finite state machine at a given instance defines an element of the primary function to be executed. The method then comprises distributing the finite state machine throughout the code to obscure one or more areas of the code.

Software tamper resistance

In overview, methods, computer programs products and devices for securing software are provided. In accordance with the disclosure, a method may comprise attaching a debugger process to a software process. During execution of the software process, operations relevant to the functionality of the code process are carried out within the debugger process. As a result, the debugger process cannot be replaced or subverted without impinging on the functionality of the software process. The software process can therefore be protected from inspection by modified or malicious debugging techniques.

Software protection from attacks using self-debugging techniques

The present invention relates in particular to a pairing method between a multimedia unit and one operator having an operator identifier, the multimedia unit having a multimedia unit identifier and receiving conditional access data from said operator, the method being characterized in that: said multimedia unit further having a function of the multimedia unit and said operator further having a function of the operator, these functions being such that the result of the application of the function of the operator to said operator key and to said multimedia unit identifier is equal to the result of the application of the function of the multimedia unit to said multimedia unit key and to said operator identifier, this result forming a pairing key between said multimedia unit and said operator.

Pairing method between a multimedia unit and at least one operator, multimedia unit, operator and personalization entity for the implementation of this method

Methods, system and devices are provided that generate a sequence of sub-keys for cryptographic operations from a main key. The main key is operated on only once to generate the sub-keys of the sequence, with a transformation comprising one or more one-way functions. The respective bit values of the sub-keys of the sequence are set using respective bit values of the one or more one-way functions. Advantageously, deriving sub-key bits from respective output bits of one or more one-way functions removes or at least reduces correlations between the main key and the sub-keys, as well as between sub-keys, making it harder or even impossible to recover the main key or other sub-keys from a single sub-key, for example as found using a side-channel attack. At the same time, by using the main key only once (rather than using the main key each time a sub-key is generated), the vulnerability of the main key to a side-channel attack is reduced, because the opportunities for recovering physical information that could lead to the discovery of the main key are reduced. Specific embodiments use parallel or chained execution of sub-functions to generate respective sub-keys. Other specific embodiments generate all sub-keys from a single one-way function in one go.

Key sequence generation for cryptographic operations

The present invention concerns the field of software verification, in particular to check whether the run-time integrity of a software application can be demonstrated. It is therefore proposed a method to verify, by a verification server, the execution integrity of an application in a target device wherein the verification server receives an application signature generated from run time application information on the target device, said signature being used to verify the execution integrity of the application in the target device, said application comprising an array of blocks, each block producing a digest, thus producing an array of digests related to the array of blocks, comprising the steps of: &#x2014;sending to the target device a message comprising a challenge and a first function, said first function defining an aggregation method, said challenge defining an aggregation instruction, &#x2014;receiving an attestation from the target device, this attestation being generated by the target device by determining for each block, the corresponding digest for said block, aggregating the digests of the blocks according to the aggregation method of the first function and the challenge to produce the attestation related to the application, &#x2014;applying a second function to the attestation by the verification server, said second function undoing the effect of the challenge thus producing an application signature independent of the challenge, &#x2014;verifying the execution integrity of the application by comparing the produced application signature with a reference signature.

Method to verify the execution integrity of an application in a target device

A block cipher method and apparatus using round repetition for providing, from a plaintext message, a ciphertext message and a global tag is disclosed; the plaintext message is converted into a plurality of ordered plaintext blocks which are successively processed during a round for computing: a cryptogram by encrypting input data using a single cryptographic key, said cryptogram comprising a first segment and a second segment; a ciphertext block by performing a first operation using, as operands: said first segment said current plaintext block and said second segment; at each next round said input data is newly determined based on the current ciphertext block and an updated reproducible data; the ciphertext message is determined by concatenating the ciphertext blocks and the global tag by a second operation using computed authentication local tags as operands.

A method of transmitting data to a receiver via a network includes transmitting a sequence of first data packets to the receiver via the network, each first data packet including payload data and identification data, the identification data identifying the respective first data packet, the identification data being different for each first data packet. The method also includes transmitting a corresponding second data packet for each first data packet to the receiver via the network, each second data packet including the data enabling identification of the corresponding first data packet and additional data related to the corresponding first data packet, the data enabling identification of the corresponding first data packet enabling the receiver to associate each second data packet with the corresponding first data packet.

Data transmission method, transmitter and receiver

In overview, an integrated circuit in accordance with the disclosure comprises first and second network interface processors which are separate processors and which are connected by a first unidirectional interconnect. The first unidirectional interconnect allows data transfer from the first network interface processor to the second network interface processor, while preventing data transfer in the reverse direction. The first network interface processor is for communication with a first network which may be a secure network and the second network interface processor is for communication with second network which may be a public network, for example an insecure public network. In this way, the processing of data received from each of the first and second networks is performed by separate processors and data can only be sent from the first network to the second network, thereby protecting the first network from the second network.

Integrated circuit

A method for watermarking an encrypted digital content stored in a content distribution network (CDN) method comprises the steps of receiving in the CDN, a non-watermarked encrypted content and marking metadata, said non-watermarked encrypted content being the result of an encryption of a non-watermarked clear content by a stream cipher process, said marking metadata indicating locations in the content suitable for a modification of said content; using a watermark formed of watermark values and corresponding to a unique identifier; and producing a watermarked encrypted content by combining in the CDN, with a combination function, the values forming the watermark with the non-watermarked encrypted content in locations indicated by the marking metadata.

Method for watermarking encrypted digital content, method and device for retrieving a unique identifier from watermarked content and content distribution network

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Penthalaz, Switzerland

Brecht Wyseur